This invention relates in general to orthopedic splints and, more particularly, to synthetic splints and packaged splints.
Many types of splints are available for orthopedic purposes such as to immobilize body portions to allow a broken bone or other injury to heal. Some of the more common types of splints include those made from plaster-of-paris, metals, high temperature plastics, low temperature plastics, and synthetic materials.
Plaster-of-paris splints are perhaps the most widely utilized splints because of their low cost and their ability to conform to the contours of the underlying body portion. Despite their widespread usage, plaster splints suffer from a number of deficiencies. Application of plaster splints can be messy since water must be used to activate the chemical reaction which results in curing of the plaster-of-paris material. Such splints also present a risk of burning the underlying skin surface because of the heat generated by the exothermic curing reaction. In order to reduce the risk of burning, the plaster is typically formulated to generate less heat by setting more slowly than would otherwise be desired, such as when rapid immobilization of the injured body portion is needed. Plaster also has a relatively low strength and the resulting splint tends to be very bulky in order to achieve the necessary strength, particularly when used to immobilize a patient's leg.
Splints made from metal and high temperature plastics require the use of special tools for forming and shaping the splint prior to application. While splints resulting from such materials are considerably stronger and more durable than plaster splints, they are significantly more costly than plaster types. Because of their high cost and the special tools required for their application, metal and high temperature plastics splints are generally unsuited for general usage.
The use of splints made from low temperature plastics is also limited by the need for a hot plate or tray of hot water to soften the plastic material prior to application. In addition to the inconvenience presented by such heating, the hot plastic presents a burn hazard to both the technician and the patient. Furthermore, the plastic material does not permit ventilation of the skin surface and maceration of the skin surface can occur.
Synthetic splints, typically layers of fiberglass cloth coated with a water-activated polyurethane resin and applied to a padding material, are quite strong and durable but are considerably more expensive and are less conformable in comparison to plaster. Synthetic splints, like plaster splints, may be unsuited for emergency usage because they require water for activation. The water which is absorbed into the padding also provides an ideal environment for bacterial growth and can cause maceration of the underlying skin, particularly when the splint is worn for an extended period of time. Moreover, the patient is placed at risk by the exothermic curing process which can generate sufficient heat to cause burning or irritation of the patient's skin. The patient and technician must also be protected from contact with the polyurethane resin during application of the splint because the resin is difficult to remove from clothing and skin surfaces.
While synthetic splints of the type described are considerably lighter than those formed from plaster, they are still heavy and bulky and contribute to patient discomfort. The edges of the splint can produce hard, needle-like structures which can abrade and pierce the skin, resulting in further discomfort and injury to the patient. Furthermore, the durability of the cured splint is limited since it is prone to delamination under stress and the fiberglass material has poor fatigue characteristics which can lead to cracking and breaking of the material under repeated loadings. Such splints are also costly to manufacture because a nitrogen environment must be provided for the assembly process. In addition, splints of this type have a limited storage life as they lose their effectiveness over a relatively short period of time.
Another type of synthetic splint which has been developed utilizes a polyvinyl acetal sponge material. The sponge material is provided in rigid preshaped configurations which are then softened in a steam chest for application to the corresponding body portion. The sponge material then returns to its hardened state after drying. While such splints provide a generally acceptable structure of relatively low strength, the requirement of a steam chest to soften the splint for application restricts the use of the splints to locations in which such a device is present. Moreover, the time required to soften and then reharden the splint often is undesirably long, particularly when rapid immobilization of the injured body portion is required, and further limits the suitable uses for the splint. Great care must also be exercised to ensure that the patient is not burned by the heated splint after it is removed from the steam chest.
Because the polyvinyl acetal sponge material of the type described does not soften sufficiently to readily conform to the contours of the underlying body part, the splint must be manufactured to a rigid preformed configuration which approximates the shape of the body portion to which it is to be applied. The use of steam to soften the splint then allows the splint to more closely conform to the body portion. A large stock of splints of various configurations, however, must be maintained in order to ensure that the needed configuration is available for use.